Guides
Hijri calendar guides
The converter, the 12 month pages and the 408 year pages tell you what a date is. These guides explain why - why the dates move about eleven days a year, why two Islamic calendars can disagree by a day, and what a calculated date can and cannot tell you.
How the Islamic calendar works, and why the dates shift every yearWhy the Hijri year is 354 or 355 days, where the missing eleven days go, how leap years work, and when a Hijri date returns to the same Gregorian day.Umm al-Qura, tabular and moon-sighting calendars comparedUmm al-Qura tables, the arithmetic tabular calendar and local crescent sighting: what each method is, how far apart they land, and which to use.How to convert a Hijri date to Gregorian by handConvert Hijri to Gregorian with pen and paper using the Julian Day Number, worked end to end - and why two converters can give you dates a day apart.Why Ramadan and Eid dates differ from country to countryWhy Ramadan and Eid start on different days in different countries, what a calculated calendar cannot tell you, and how to plan around a one-day gap.What year is it in the Islamic calendar?Any Gregorian year overlaps two Hijri years, and the boundary moves. How to find the Hijri year for any date, and why no fixed offset works.Your Hijri birthday, and your age in Islamic yearsWhy an age in Hijri years is always higher than the Gregorian age, why a Hijri birthday moves 11 days a year, and how to work out both for any birth date.Leap years in the Hijri calendarA Hijri leap year is a 355-day year, not a leap day in February. How the tabular 30-year cycle works and why Umm al-Qura disagrees on which years are long.The four sacred months of the Islamic calendarMuharram, Rajab, Dhu al-Qadah and Dhu al-Hijjah are the sacred months. Which they are, why three run consecutively, and when they fall each Gregorian year.
Go straight to the dates
Every guide links into the pages that hold the data.